These types of ground milling machines are usually used in road and path construction and in surface mining of natural resources. The most often comprise a machine frame or chassis, an operator's platform, and multiple running gears. Furthermore, they have a drive engine, which is usually a diesel engine, by which the ground milling machine, particularly its running gears and the working device, is powered. These types of ground milling machines are known, for example, from DE 10 2013 020 679 A1 and DE 10 2013 002 639 A1 of the same applicant.
The working device of the ground milling machine is a milling drum that is typically mounted in a milling drum box, which is closed to the sides and to the top and is open towards the ground, such that it can be rotated about its rotation axis, said rotation axis most often extending horizontally and transversely to the working direction. The milling drum is designed, for example, in the form of a hollow cylinder and equipped with a plurality of tool devices on its outer jacket surface. The tool devices comprise, for example, respectively one milling chisel and one chisel holder. The chisel holder is connected to the milling tube of the milling drum and holds the milling chisel. The milling chisel may be, for example, an integral piece or, alternatively, it may comprise multiple components, particularly a base holder and a quick-change chisel holder attached to the base holder, which in turn is designed for receiving the milling chisel. Reference is made to DE 10 2010 044 649 A1 and DE 10 2010 051 048 A1 of the same applicant with respect to the structure of such tool devices. During work operation of the ground milling machine, the tool devices are driven into the ground through the rotation of the milling drum, thereby milling the ground. As the ground milling machine advances in the working direction during milling operation, the ground material is milled along a milling track. Depending on the machine type and application, the loose milled material may then be transferred via a discharge conveyor to a transport vehicle and hauled away by it (typically in the case of surface miners and road milling machines) or it may remain on the surface (typically in the case of stabilizers and recyclers).
During the milling process, the tool devices, particularly the milling chisels, are subjected to heavy wear. The milling chisels of the tool devices must therefore be regularly replaced. It may likewise occur that the chisel holders are also either heavily worn or damaged due to a milling chisel breaking. In this case, the chisel holder must also be replaced. For chisel holders which comprise a base holder and a quick-change chisel holder, it may suffice if the quick-change chisel holder is replaced together with the milling chisel.
As regards the mounting of the milling chisel, it is known to attach it in the chisel holder so that the chisel can rotate. So-called clamping sleeves are usually used for this purpose. However, the rotatable mounting of the chisel in the chisel holder also involves disadvantages. In addition to the increased material use and installation effort, the rotation of the milling chisel itself results in increased wear between the chisel shaft and the clamping sleeve as well as between the wear plate and the holder. Therefore, it is also known to arrange the milling chisel in or on the chisel holder such that the chisel cannot rotate. To this end, the milling chisel may be soldered, for example, directly onto the chisel holder or mounted in the chisel holder by means of a press fit. This type of connection is frequently considered, for example, if the used milling chisels include materials with a relatively high degree of hardness. The disadvantage of such design variants then lies in the fact that once the milling chisel has reached its wear limit, the change procedure is relatively complex. It is then frequently necessary to replace the chisel holder or the quick-change chisel holder together with the milling chisel as a modular unit, even if only the milling chisel is actually worn and needs to be changed. Furthermore, the new installation of the milling chisel is relatively time consuming and complicated. In addition, especially when using soldered connections, the hardness or resistance of the material in the wear area is diminished through the heat input in the chisel holder during soldering.